From d64d80a2cde94f3e89caebd27240be419fec5b81 Mon Sep 17 00:00:00 2001 From: Daniel Borkmann Date: Thu, 2 Apr 2015 14:28:30 +0200 Subject: [PATCH] netfilter: x_tables: don't extract flow keys on early demuxed sks in socket match Currently in xt_socket, we take advantage of early demuxed sockets since commit 00028aa37098 ("netfilter: xt_socket: use IP early demux") in order to avoid a second socket lookup in the fast path, but we only make partial use of this: We still unnecessarily parse headers, extract proto, {s,d}addr and {s,d}ports from the skb data, accessing possible conntrack information, etc even though we were not even calling into the socket lookup via xt_socket_get_sock_{v4,v6}() due to skb->sk hit, meaning those cycles can be spared. After this patch, we only proceed the slower, manual lookup path when we have a skb->sk miss, thus time to match verdict for early demuxed sockets will improve further, which might be i.e. interesting for use cases such as mentioned in 681f130f39e1 ("netfilter: xt_socket: add XT_SOCKET_NOWILDCARD flag"). Signed-off-by: Daniel Borkmann Signed-off-by: Pablo Neira Ayuso --- net/netfilter/xt_socket.c | 95 ++++++++++++++++++++------------------- 1 file changed, 50 insertions(+), 45 deletions(-) diff --git a/net/netfilter/xt_socket.c b/net/netfilter/xt_socket.c index 895534e87a47..e092cb046326 100644 --- a/net/netfilter/xt_socket.c +++ b/net/netfilter/xt_socket.c @@ -143,13 +143,10 @@ static bool xt_socket_sk_is_transparent(struct sock *sk) } } -static bool -socket_match(const struct sk_buff *skb, struct xt_action_param *par, - const struct xt_socket_mtinfo1 *info) +static struct sock *xt_socket_lookup_slow_v4(const struct sk_buff *skb, + const struct net_device *indev) { const struct iphdr *iph = ip_hdr(skb); - struct udphdr _hdr, *hp = NULL; - struct sock *sk = skb->sk; __be32 uninitialized_var(daddr), uninitialized_var(saddr); __be16 uninitialized_var(dport), uninitialized_var(sport); u8 uninitialized_var(protocol); @@ -159,10 +156,12 @@ socket_match(const struct sk_buff *skb, struct xt_action_param *par, #endif if (iph->protocol == IPPROTO_UDP || iph->protocol == IPPROTO_TCP) { + struct udphdr _hdr, *hp; + hp = skb_header_pointer(skb, ip_hdrlen(skb), sizeof(_hdr), &_hdr); if (hp == NULL) - return false; + return NULL; protocol = iph->protocol; saddr = iph->saddr; @@ -172,16 +171,17 @@ socket_match(const struct sk_buff *skb, struct xt_action_param *par, } else if (iph->protocol == IPPROTO_ICMP) { if (extract_icmp4_fields(skb, &protocol, &saddr, &daddr, - &sport, &dport)) - return false; + &sport, &dport)) + return NULL; } else { - return false; + return NULL; } #ifdef XT_SOCKET_HAVE_CONNTRACK - /* Do the lookup with the original socket address in case this is a - * reply packet of an established SNAT-ted connection. */ - + /* Do the lookup with the original socket address in + * case this is a reply packet of an established + * SNAT-ted connection. + */ ct = nf_ct_get(skb, &ctinfo); if (ct && !nf_ct_is_untracked(ct) && ((iph->protocol != IPPROTO_ICMP && @@ -197,10 +197,18 @@ socket_match(const struct sk_buff *skb, struct xt_action_param *par, } #endif + return xt_socket_get_sock_v4(dev_net(skb->dev), protocol, saddr, daddr, + sport, dport, indev); +} + +static bool +socket_match(const struct sk_buff *skb, struct xt_action_param *par, + const struct xt_socket_mtinfo1 *info) +{ + struct sock *sk = skb->sk; + if (!sk) - sk = xt_socket_get_sock_v4(dev_net(skb->dev), protocol, - saddr, daddr, sport, dport, - par->in); + sk = xt_socket_lookup_slow_v4(skb, par->in); if (sk) { bool wildcard; bool transparent = true; @@ -225,12 +233,7 @@ socket_match(const struct sk_buff *skb, struct xt_action_param *par, sk = NULL; } - pr_debug("proto %hhu %pI4:%hu -> %pI4:%hu (orig %pI4:%hu) sock %p\n", - protocol, &saddr, ntohs(sport), - &daddr, ntohs(dport), - &iph->daddr, hp ? ntohs(hp->dest) : 0, sk); - - return (sk != NULL); + return sk != NULL; } static bool @@ -327,28 +330,26 @@ xt_socket_get_sock_v6(struct net *net, const u8 protocol, return NULL; } -static bool -socket_mt6_v1_v2(const struct sk_buff *skb, struct xt_action_param *par) +static struct sock *xt_socket_lookup_slow_v6(const struct sk_buff *skb, + const struct net_device *indev) { - struct ipv6hdr ipv6_var, *iph = ipv6_hdr(skb); - struct udphdr _hdr, *hp = NULL; - struct sock *sk = skb->sk; - const struct in6_addr *daddr = NULL, *saddr = NULL; __be16 uninitialized_var(dport), uninitialized_var(sport); - int thoff = 0, uninitialized_var(tproto); - const struct xt_socket_mtinfo1 *info = (struct xt_socket_mtinfo1 *) par->matchinfo; + const struct in6_addr *daddr = NULL, *saddr = NULL; + struct ipv6hdr *iph = ipv6_hdr(skb); + int thoff = 0, tproto; tproto = ipv6_find_hdr(skb, &thoff, -1, NULL, NULL); if (tproto < 0) { pr_debug("unable to find transport header in IPv6 packet, dropping\n"); - return NF_DROP; + return NULL; } if (tproto == IPPROTO_UDP || tproto == IPPROTO_TCP) { - hp = skb_header_pointer(skb, thoff, - sizeof(_hdr), &_hdr); + struct udphdr _hdr, *hp; + + hp = skb_header_pointer(skb, thoff, sizeof(_hdr), &_hdr); if (hp == NULL) - return false; + return NULL; saddr = &iph->saddr; sport = hp->source; @@ -356,17 +357,27 @@ socket_mt6_v1_v2(const struct sk_buff *skb, struct xt_action_param *par) dport = hp->dest; } else if (tproto == IPPROTO_ICMPV6) { + struct ipv6hdr ipv6_var; + if (extract_icmp6_fields(skb, thoff, &tproto, &saddr, &daddr, &sport, &dport, &ipv6_var)) - return false; + return NULL; } else { - return false; + return NULL; } + return xt_socket_get_sock_v6(dev_net(skb->dev), tproto, saddr, daddr, + sport, dport, indev); +} + +static bool +socket_mt6_v1_v2(const struct sk_buff *skb, struct xt_action_param *par) +{ + const struct xt_socket_mtinfo1 *info = (struct xt_socket_mtinfo1 *) par->matchinfo; + struct sock *sk = skb->sk; + if (!sk) - sk = xt_socket_get_sock_v6(dev_net(skb->dev), tproto, - saddr, daddr, sport, dport, - par->in); + sk = xt_socket_lookup_slow_v6(skb, par->in); if (sk) { bool wildcard; bool transparent = true; @@ -391,13 +402,7 @@ socket_mt6_v1_v2(const struct sk_buff *skb, struct xt_action_param *par) sk = NULL; } - pr_debug("proto %hhd %pI6:%hu -> %pI6:%hu " - "(orig %pI6:%hu) sock %p\n", - tproto, saddr, ntohs(sport), - daddr, ntohs(dport), - &iph->daddr, hp ? ntohs(hp->dest) : 0, sk); - - return (sk != NULL); + return sk != NULL; } #endif -- 2.30.2